F5 injection handwheel backlash — ignition delay unstable

On F5, the injection handwheel sets compression ratio. Large backlash lets the scale sit while the actual ratio still moves — ignition delay wanders inside a small band.

Quantify first

Seat in one direction, reverse, and read the scale difference. That difference is backlash. Loose locknuts, slipping dials and worn screws can feel similarly “loose” but need different fixes.

After parts

Check delay with two reference points — not only that the wheel feels tighter. Related: cetane repair, cetane inspection.